Abstract: In a solenoid-controlled valve assembly a biasing means (21) is adapted to apply a resisting force to a spool (22) in a direction opposite to the direction substantially of a force applied by an armature (14), and engagement between at least one of the spool and the biasing means and the spool and the armature is through an engagement means defining a single point of contact. The spool (22) may be provided with at least one land adapted to connect and disconnect two flow passages (6, 8), and the first ends of the two passages are spaced apart in a direction parallel to the axis of the bore by a smaller distance than the spacing between the second ends of the passages.

Abstract: An actuator device self-contained within a housing and adapted to move an object. The actuator device includes a movable piston positioned in a cylinder portion of the housing. The cylinder portion defines a longitudinal axis, whereby the piston is movable along the longitudinal axis in response to an accumulation of air pressure within the cylinder portion. The actuator device also includes a rod coupled to the piston for movement with the piston. The rod at least partially extends outside of the housing to couple to the object. Further, the actuator device includes an air compressor located within the housing. The air compressor transfers air from a location in the housing outside the cylinder portion to a location inside the cylinder portion.

Abstract: A hydraulic circuit branch includes a hydraulic actuator, such as a cylinder, and an assembly of one or more electrohydraulic proportional valves connected in series between a pressurized fluid supply line and a tank return line. The force acting on the hydraulic actuator is determined by sensing fluid pressures produced by the hydraulic actuator. Pressures in the supply and tank return lines also are sensed. The sensed pressures and a desired velocity for the hydraulic actuator are employed to determine an equivalent flow coefficient, which characterizes fluid flow through the hydraulic circuit branch, either a conduction or restriction coefficient may be derived. The equivalent flow coefficient is used to determine how to activate each electrohydraulic proportional valve to achieve the desired velocity of the hydraulic actuator. The equivalent flow coefficient also is employed to control the pressure levels in the supply and tank return lines.

Abstract: The circuit comprises first and second power lines connected to a port of a first actuator chamber and to the port of a second actuator chamber, respectively; a supply line and a discharge line connected to a supply source and to a discharge reservoir; a first sliding member valve capable of connecting the first power line to the supply and discharge lines under the control of pilot pressures transmitted to the first sliding member valve by a first pair of pilot lines; and a second sliding member valve capable of connecting the second power line with the supply and discharge lines under the control of pilot pressures transmitted to the second sliding member valve by a second pair of pilot lines.

Abstract: A system and method for controlling an electro-hydraulic valve arrangement to perform a pump check function are provided. The system includes an electro-hydraulic valve arrangement disposed between a source of pressurized fluid and a hydraulic actuator. Pressure sensors are provided to sense a source pressure representative of the fluid pressure between the source of pressurized fluid and the electro-hydraulic valve arrangement and an actuator pressure representative of the fluid pressure between the electro-hydraulic valve arrangement and the actuator. A control device receives a signal to open the electro-hydraulic valve arrangement to provide a requested flow rate to the hydraulic actuator. The received signal is modified to prevent fluid flow through the electro-hydraulic valve arrangement when the source pressure is less than the actuator pressure.

Abstract: A solenoid valve control is described, having a switching output stage for controlling a solenoid valve, an arrangement for preselecting a valve opening time, and an arrangement for preselecting a pressure over the valve. Also provided is an arrangement for determining a valve control time from the preselected valve opening time and the preselected pressure over the valve. A method is also described for controlling a solenoid valve which can be carried out to advantage with this solenoid valve control.

Abstract: A pressure compensator for use in a control system for an electro hydraulic-implemented work element being operated through the use of operator input control mechanisms generating operator input signals upon the application thereof, the control system including an actuator coupled thereto for controlling the operation thereof, the pressure compensator determining a pressure compensator coefficient to be applied to an operator input signal to compensate for changes of pressure drop across a valve in communication with the actuator. The pressure compensator coefficient is used to produce an input flow control signal for inputting to the valve to control the amount of hydraulic fluid that flows therethrough to the actuator so that a desired velocity of the actuator is achieved.

Abstract: A compact hybrid actuator has a fluid pump (20) arranged to supply fluid to an actuator (44). The pump has at least one electrically-powered solid-state pump driver (21) provided with a displacement element (22). The position of this displacement element modulates the volume of a fluid chamber (23). A driven valve (24) is operatively arranged to control the flows of fluid with respect to the pump chamber, and has one member (29) movable relative to a body (28) to modulate the opening of ports (25, 26) so as to form at least one three-way valve. A valve driver (31) is operatively arranged to operate the driven valve. Electrical power is provided to each valve and to the valve driver so as to operate these various elements in synchronism with one another. The improved pump driver and driven valve may be operated at frequencies in excess of 1 kHz.

Abstract: A method is provided for controlling hydraulic flow through a valve. The method includes determining a pressure drop across the valve and estimating a flow rate through the valve based on the pressure drop and a displacement of the valve. A command signal to actuate the valve is computed based on a desired flow rate and the estimated flow rate through the valve.

Abstract: An integral valve-cylinder assembly and a fork folding hydraulic system for front loading waste collection vehicles is provided that allows the forks to be full tucked for over-the-road travel and without exceeding the vehicle height limit that uses a multi-port hydraulic cylinder integrated with a remotely activated valve that is operated with a single control valve from within the vehicle cab.

Abstract: A method and a device for the supply of electrical loads in or on a pneumatic device with electrical power energy. The pneumatic device is connected by way of a pneumatic line with a source of pressure. The transmission of power energy to the pneumatic device takes place using acoustic waves, microwaves, changes in pressure or a flow of gas in the pneumatic line. Conversion of such transmitted energy into the electrical supply energy occurs in or on the pneumatic device. This means that electrical lines for electrical power supply may be dispensed with and that the transmission of energy takes place only by way of the pneumatic line.

Abstract: A fluid control system may comprise a pump, a tank, and an actuator including a working chamber. The system may be operative to control rotational movement of a swing structure and movement of an least one implement. A valve assembly may be configured to control fluid communication between the working chamber and the tank and to control fluid communication between the working chamber and the pump. An input device may be operative to selectively control movement of the swing structure. The system may include a controller in communication with the valve assembly and the input device. The controller may be configured to control a flow condition of the working chamber through a sensed pressure condition of the working chamber and a command from the input device.

Abstract: In the construction machinery equipped with an engine, a hydraulic control unit and a machine controller, there is provided an antitheft device for the construction machinery, which can prevent the engine from starting and the hydraulic control unit from working with reliability no matter how the starter circuit of the engine is modified. The initial state of the machine controller is so set that the fuel injection by a fuel injection unit of the engine is halted and that the operations of control units in the hydraulic control unit are halted, and an antitheft control unit is provided to release the initial state of the machine controller upon receiving a release signal from the antitheft control unit.

Abstract: The present invention intends to provide a hydraulic signal output device having a smaller installation space, and thereby enabling to make an installation space of hydraulic machines in an operation room smaller and that of other than the hydraulic machines larger. In addition to this, the present invention intends to allow externally restricting an operation in the operation room. In order to attain the intentions, in a hydraulic signal output device of the present invention, a PPC valve, an EPC valve and a shuttle valve are integrally formed. In one invention, in addition to the above, a pressure oil output port in a pressure-reducing valve in the PPC valve is communicated with a pressure oil input port of a switching valve in an electromagnetic valve, and a pressure oil output port of the switching valve in the electromagnetic valve is communicated with a pilot pipe line.

Abstract: A device for hydraulic adjustment of rollers of strand guiding segments of a strand casting device has hydraulic cylinders which are separated by a piston with piston rod into a cylinder chamber and an annular cylinder chamber, respectively. The cylinder chambers can be connected by control members alternatingly and in opposite directions as well as simultaneously with a pressure source and a pressure sink, wherein on-off valves are provided as control members.

Abstract: A system and method for controlling an electro-hydraulic valve arrangement to provide make-up fluid to a hydraulic actuator are disclosed. The system includes an electro-hydraulic valve arrangement actuated by a control lever and disposed between a pump having a stand-by pressure and a hydraulic actuator. A pressure, representative of the fluid in the hydraulic actuator, is sensed and compared to the stand-by pressure of the pump. The control of the control lever over the electro-hydraulic valve arrangement is overridden when the difference between the pump stand-by pressure and the pressure of the fluid in the hydraulic actuator is greater than a predetermined pressure limit.

Abstract: The invention disclosed is a direct driven, smart material actuated servovalve providing very high actuation control bandwidth for moderate to large flow systems. The servovalve is comprised of a valve body and a valve spool, a smart material element such as a piezoelectric, electrostrictive or magnetostrictive material, and a mechanical lever. The lever is mounted to a pivot support in the valve body and is positioned relative to the smart material element and valve spool such that expansion/contraction motion induced into the smart material element enforces motion on the first end of the mechanical lever. This motion is amplified by the lever at the second end of the lever and drives the end of the valve spool. The resulting amplified motion causes the valve spool to shift along its longitudinal axis of sufficient distance to afford high bandwidth valve spool positioning on large flow valves.

Abstract: A fluid power operate linear drive possessing a slab housing (2) with an elongated cross sectional outline, in which a plurality of receiving spaces (8) are arranged extending in a common housing plane adjacent to each other in the direction of the longitudinal axis (3) of the cross section. At one first narrow side (21) of the housing there is a piston receiving space (12) extending in the longitudinal direction containing a piston (13) connected with an outwardly running force output part (16). At the opposite second narrow housing side (22) there is an electronic circuitry receiving space (23) containing electronic valve control circuitry (24). Between the piston receiving space (12) and the electronic circuitry receiving space (23) there is at least one valve receiving space (26), which contains a control valve means (25), which is able to be electrically operated and serves for the control of fluid actuation of the piston (13).

Abstract: Hydraulic actuators and/or other parameters on a work attachment for a skid steer loader are controlled with a wireless remote control kit. The kit includes a manual input device and transmitter mounted to the skid steer loader and a receiver on the work attachment that communicates with the transmitter. The receiver directly couples the manual input from the vehicle operator to the solenoid valves that control hydraulic flow to the hydraulic actuators on the work attachment, without processing by an electronic controller. The response of hydraulic actuators directly corresponds to the manual input provided by the vehicle's operator. The manual input device, transmitter module and the independent power source may be self-contained in a module that is attachable and detachable to skid steer loader. The module can be removed and transferred along with the attachment such that the attachment is usable with different skid steer loaders.

Abstract: A control device for hydraulic, mechanical, and hydraulic-mechanical components has a housing in which at least one drive element is arranged. The drive element is a piezo element having a voltage-dependent stroke-force behavior. The piezo element acts directly onto the component to be actuated. The control device with the piezo element replaces actuating devices such as solenoids, complete valves, as well as coupling and switching mechanisms.

Abstract: The present invention relates to an electro-pneumatic positioner for use with a pneumatically controlled two-chamber actuator comprising a first valve unit (10) comprising a first air supply valve (14) and a first air outlet valve (37) connected to a conduit (30, 38, 50), which in turn is connectable to a chamber of the actuator, a second valve unit (12) comprising a second air supply valve (14′) and a second air outlet valve (37′) connected to a conduit (30′, 38′, 50′), which in turn is connected to a second chamber of the actuator; a first control device (60, 74) acting on the first air supply valve, which first control device comprises a first control valve (60); a second control device (60′, 76) acting on the said second air supply valve, which second control device comprises a second control valve (60′).

Abstract: In a solenoid-controlled valve assembly a biasing means (21) is adapted to apply a resisting force to a spool (22) in a direction opposite to the direction substantially of a force applied by an armature (14), and engagement between at least one of the spool and the biasing means and the spool and the armature is through an engagement means defining a single point of contact. The spool (22) may be provided with at least one land adapted to connect and disconnect two flow passages (6, 8), and the first ends of the two passages are spaced apart in a direction parallel to the axis of the bore by a smaller distance than the spacing between the second ends of the passages.

Abstract: An actuating device (1) for the rotation of a stand (4) of a vehicle, such as a motorcycle or scooter, between a standing position and a rest position, and allowing also the reverse maneuver in order to rotate the stand from the position of vehicle on the stand up to that in which the vehicle lowers spontaneously. At least one hydraulic actuator (1) is provided that operates, between a first and a second position, an actuating member (7) or piston rod that engages with the stand (4) up to bringing it respectively from the rest position to the standing position. A flow control hydraulic circuit delivers pressurized liquid to the actuator (1) for moving the actuating member (7) from the first to the second position, and allows the back stroke of the actuating member (7) to the first position when the flow of the liquid ceases, whereby the stand (4) can be brought back to said rest position independently from the actuating member (7).

Abstract: A method and device for the transmission of control and/or sensor signals between an electronic control and/or data receiving means and a pneumatic device, which are connected together by means of a pneumatic line of flexible plastic material. For the transmission of the signals using acoustic signals, microwaves or changes in pressure in the gaseous medium in the line the control and/or data receiving means and the pneumatic device are provided with at least one first converter for the conversion of electrical signals into acoustic signals or changes in pressure into electrical signal. Accordingly it is possible for electrical lines, otherwise needed for data transmission, to be dispensed with and data transmission takes place by way of the gaseous medium in the pneumatic line.

Abstract: The invention relates to a controllable adjustment and damping device comprising at least one pressure chamber (4) filled with hydraulic fluid, a fluid container (11), a pump (5) connecting the pressure chamber to the fluid container, a compensating volume (8) and a return line (13) with a passthrough valve (7). An electro-rheological fluid or magneto-rheological fluid is used as a hydraulic fluid (6) which exerts pressure upon a piston (3) that juts out into the pressure chamber or on a membrane (17), the intensity thereof being controlled by the passthrough valve.

Abstract: An assembly of a pair of electrically operated bidirectional proportional control valves and a four-way direction control valve governs the flow of fluid to and from a hydraulic cylinder. The four-way direction control valve alternately connects a pump supply line to one of a pair of intermediate conduits and a tank return line to the other intermediate conduit. That connection determines the direction of movement of the cylinder piston. The intermediate conduits are coupled to chambers of the cylinder by a separate one of the proportional control valves which meters the fluid flow to or from the respective chamber. Thus the proportional control valves control the rate of piston movement.

Abstract: The invention is based on an apparatus (10) for regulating the pressure in a hydraulic circuit that comprises an electrically triggerable pressure-control valve (12), a receptacle device (14) in which the pressure-control valve (12) is installed, and means (54, 64) for damping pressure pulsations. In order to save space, simplify the manufacture of the receptacle device (14), and save additional holding elements, it is proposed according to the invention that the means (54, 64) for damping pressure pulsations be designed as integral components of the pressure-control valve (12).

Abstract: A hydraulic control system having a pump for delivering fluid under pressure from a fluid reservoir, a hydraulic actuator selectively driven by the fluid, the system comprises a main flow control valve connected between the pump and the actuator for selectively providing the fluid to and from the actuator, and a control unit connected to the main flow control valve for controlling operation of the main flow control valve to control the rate of change of the area of the main flow control valve relative to the delivery of fluid from the pump, and the control unit connected to the pump to increase or decrease the actual pump command proportional to the inverse of the pump command.

Abstract: An apparatus and method of controllably moving a moveable element within a hydraulic motor is disclosed. A lever device produces an operator command signal indicative of a desired velocity of the moveable element. An electronic controller receives the operator command signal, compares the operator command signal to a limit value, and produces a limited command signal in response to the operator command signal being greater than the limit value. An electrohydraulic controller receives the operator command signal and responsively controls the movement of the moveable element.

Abstract: A solenoid operated valve with a single inlet for connection to a pump and a control signal outlet for connection to a power assist steering actuator and a bleed port for connection to a pressure control valve. The valve has a poppet rod extending through an annular valve seat, with a pressure equalization passage extending through the poppet and rod to balance the inlet pressure forces acting on the poppet and rod. The valve provides a low residual flow when the solenoid is de-energized and proportionally increases flow as current in the solenoid is increased and gives substantial linearity.

Abstract: A hydraulic steering arrangement, having a steering value, which connects a steering motor with a pump, and which has a slide with two front sides, the slide being adjustable by means of a pressure fluid both through a hydraulic steering unit with a steering hand wheel and through an electro hydraulic steering unit with a control pressure generator. The two steering units have working connections and the front sides of the slide are connected with shuttle valves, each of which is connected with hydraulic steering unit on the one side and with the electro hydraulic steering unit on the other side. A valve arrangement connects the working connection of both steering units, which has the highest pressure, with one front side of the slide, and the working connection of both steering units, which has the lowest pressure, with the other front side of the slide.

Abstract: Main piston servo-actuation system, with hydromechanic self-contained failure detection device, working with hydraulic fluid supplied by a pump, including two servovalves (1 and 2) which are identical in design, controlling a piston (3) mechanically linked to a position transducer (4) according to the electrical demand (6, 7) supplied by the feedback position control loops (8 and 9) for the servovalves (1 and 2) to the torque motors (12 and 13) of the servovalves. These loops (8 and 9) receive the same piston position request, and they are given feedback at the same time with the same position signal fed by the position transducer (4). The system is furthermore compensated by two pressure selection valves (14 and 15) and by its own interconnection servo lines.

Abstract: The system controls the position of a pneumatically operated valve using an electrical control signal from a controller. A pilot circuit of the system has multiple piezo valves that are subject to electrical signals from the controller to provide pneumatic output signals to a volume booster circuit of the system. Relatively small volume pneumatic pilot signals from the piezo valves are used to determine the opened or closed state of higher volume valve assemblies of the booster circuit which connect or disconnect the actuator of the valve to be operated with a source of pressurized gas. Both the piezo valves and the booster valve assemblies are subjected to gas at the same operating pressure, but the surface area of pistons in the booster valve assemblies exposed to the piezo valves is substantially larger than the surface area of the pistons exposed to operating pressure such that the pneumatic signals shift the pistons even when pressure is the same on both sides thereof.

Abstract: An improved control system for die casting or similar machines wherein a closed loop velocity feedback circuit is supplemented with an integration circuit and two filtering circuits to compensate for the frequency response of the pilot valve in the die casting machine. The integration circuit serves to more accurately cause the velocity of an element being controlled to match the desired/commanded velocity, and also caused the velocity to more rapidly match the desired/commanded velocity.

Abstract: A power machine or a skid steer loader that is driven by an engine and has hydraulic pump, hydraulic fluid conduit, a hydraulic motor in fluid communication with a hydraulic fluid conduit and a valve that is operated or actuated by linear actuator such that the linear actuator is mounted directly on the valve block.

Abstract: A hydraulic circuit with one or more electrically operated hydraulic distributors is provided for an agricultural or earthmoving machine. A pump unit supplies pressurized fluid to the hydraulic distributors which, in turn, supply the pressurized fluid, on command, to the hydraulic power take-offs of the hydraulic circuit. An electronic central control unit controls the electrically operated valves of the hydraulic distributors to regulate supply of the pressurized fluid to the hydraulic power take-offs. The hydraulic circuit also includes a self-calibrating device for determining, on command, the position, in a reference plane, of the response curves of individual electrically operated valves, so that the pressurized fluid supply set by the driver of the vehicle for any one hydraulic power take-off always corresponds exactly with the amount actually supplied by the take-off.

Abstract: Various work machines in which safety of operation and operation efficiency can be enhanced in accordance with variation in the kind of operation and operation condition when operation is carried out based on a previously set operation mode of an operation machine, and operation speed of the operation machine or running speed of the work machine can finely be adjusted is provided. The work machine comprises mode switching means having a mode switching switch and the like of operation modes of one or more operation machines. A speed finely-adjusting switch is disposed for finely adjusting an operation speed and/or a running speed to values out of range set in each mode by manual operation. An engine, a pump, a flow rate adjusting valve disposed in a driving circuit of one or more operation machine and running motor and the like are operated by a signal output by operating the speed finely-adjusting switch, and the engine revolution number and the pump discharge amount are adjusted.

Abstract: A self-calibrating method and system 10 for controlling a hydraulically operated device, such as a clutch actuator 24 in an automatic power transmission, provides a pressure switch 30 in the hydraulic circuit that provides feed-back to the controller 32 when the hydraulic fluid pressure has reached a set point level. Pressure switch 30 provides a signal to controller 32 that allows the controller to compare the control signal at the pressure set point level with that of the calibrated curve for adjusting the calibration curve.

Abstract: Apparatus for equalizing pressure between two conduits including means for sensing pressure in said conduits; valve means communicating between said conduits, said valve means adapted to open so as to equalize pressure between said conduits.

Abstract: A line vent arrangement is provided to selectively vent pressurized fluid from an actuator in an electro-hydraulic system when an engine of a machine has been shut down. This is accomplished by providing a pressure storage arrangement in parallel with a source of pressurized pilot fluid and an electrically controlled valve that is movable to a position to connect the pressure storage arrangement to the electro-hydraulic directional control valve when the engine of the machine has been shut down.

Abstract: A hydraulic control arrangement which has a directional control valve, a hydraulic pump and a two-way cartridge valve constructed as a seat valve. The directional control valve is connected to an inlet line and to a discharge line leading to a tank. Leading off from it is a load line leading to a hydraulic load. The hydraulic pump draws pressure medium from a tank and discharges it into the inlet line. The two-way cartridge valve is arranged in the inlet line and, in a closed position, isolates a second inlet line section leading off from the latter to the directional control valve from a first inlet line section running between the two-way valve and the hydraulic pump.

Abstract: An incrementally positionable ball valve for use in the fluid circuit of a refrigeration or air conditioning system which can be remotely controlled by a low amperage control signal is disclosed. The ball valve harnesses the pressurized refrigerant from the fluid circuit in which it is installed as the primary power medium to actuate the valve. A sensor provides feedback to a controller relating to the incremental position of the valve. The controller then controls the operation of the valve in accordance with predetermined criteria. In another embodiment, the ball valve incorporates locator detents so that its incremental position can be determined by an operator manually controlling the valve. In still another aspect of the invention, a restrictor is provided for varying the flow capacity of the valve.

Abstract: A vehicle speed control system includes a high speed/low speed selection switch and a speed control relay connected to a voltage source through a switched power line. The speed selection switch includes an input connected to the power line through the speed control relay. One output on the speed control switch is connected to an electrohydraulic valve which controls the speed range on a vehicle. The state of the electrohydraulic valve is dependent both on the switch position and on the state of the relay. The relay is deactivated when the power line is switched off and changes back to an activated state to allow high speed operation only if the speed selection switch is first placed in the low speed position after the vehicle power line is switched on. If the selection switch is in the high speed position when the power line is on, the speed control relay will remain inactivated until the selection switch is moved to the low speed position.

Abstract: An apparatus for adjusting an operating speed of a pneumatic valve 1 by means of a solenoid valve 2 including a disk-shaped orifice block 5 having a plurality of orifices 22-25 of different aperture sizes formed therein, and the orifice block is arranged rotatably between a sub-base 3 of the solenoid valve 2 and a main block 6. By rotating the orifice block 5, any one of said plurality of orifices formed in the orifice block 5 can be selectively inserted into the fluid passage between the pneumatic valve 1 and the solenoid valve 2. The operating speed of the pneumatic valve 1 can be easily adjusted in a digital manner, and the water hammer phenomenon can be effectively prevented.

Abstract: An hydraulic valve has a flow/pressure characteristic matched to that of a pump with which it is used. The valve has a housing with a fluid inlet in its side and an outlet at one end. A shuttle is movable along the housing under control of a proportional solenoid, to vary the amount by which an edge of the shuttle covers the inlet and thereby controls flow of fluid through the valve. The shuttle has a flange one end located between the inlet and outlet so that fluid flowing from the inlet to the outlet applies pressure to one side of the flange and displaces the shuttle to close the inlet. In this way, an increase in pressure tends to reduce the effective size of the inlet aperture to compensate for pressure variation.

Abstract: An electromechanical bypass mechanism is provided for use in a hydrostatic transmission, to enable the user to open or close a bypass to the hydraulic circuit of the transmission through use of an switch mechanism attached to the bypass mechanism in the circuit. The invention also comprises an improved neutral feature for hydrostatic transmissions, with a switch connected to the control mechanism for the unit, whereby the switch is activated to place the unit in bypass when said mechanism is placed in the neutral location. A means is provided for opening and closing a shunt or bypass between the high pressure side and the low pressure side of the hydrostatic system which is triggered by an electrical signal.

Abstract: A apparatus for use with an open center steering valve (3) of a hydraulic power-assisted steering unit of a motor vehicle. The apparatus comprises an electric motor operated pump (5) and a hydraulic accumulator (7) for storing a pressurized quantity of hydraulic fluid. The hydraulic accumulator (7) is hydraulically connected to the pump (5). The pump (5) supplies the pressurized hydraulic fluid to the hydraulic accumulator (7). The apparatus further comprises a valve arrangement (10) for controlling hydraulic fluid flow from the hydraulic accumulator (7). The valve arrangement (10) has a riser (25), a slide valve (19), a valve seat (21), and an electromagnet. The riser (25) is hydraulically connected to the pump (5). The valve seat (21) has an opening which hydraulically connects the riser (25) and the hydraulic accumulator (7).

Abstract: In a pressure motor for electro-rheological fluids comprising a housing (1) surrounding two operating chambers (A, B), a piston (3) moveable in the housing (1), an inlet channel (22) for supplying, and an outlet channel (23) for discharging an electro-rheological fluid, and electro-rheological valves (1a, 1b, 2a, 2b) comprising an annular gap (8) which in each case connects an operating chamber (A and B) to the inlet channel (22) or the outlet channel (23) and whose boundary surfaces form electrodes for the generation of an electric field, the electro-rheological valves (1a, 1b, 2a, 2b) are formed by bores (6) which penetrate through the housing wall in the longitudinal direction and by mandrels (7) which are arranged in the bores (6) and are insulated from the housing (1), where the bores (6) and the mandrels (7) co-define annular gaps (8) of a constant gap width and the mandrels (7) can be connected to a high voltage and the housing (1) can be connected to earth potential.

Abstract: A hydraulic valve control system that includes a plurality of digitally actuated magnetically-latchable four-way valves that directly or indirectly control the position of a hydraulic actuator. The digitally actuated magnetically-latchable four-way valves are controlled by a controller that can control the valves in accordance with a servo routine. The servo routine may include the computation of a plurality of cost functions and the selection of an action that corresponds to the lowest cost.

Abstract: When a start SW 3 is pressed, a one-shot multivibrator circuit 15 turns on and releases a pulse. The pulse is transmitted to a self-hold circuit 16 which in turn stays in self-hold mode and releases an H level output continuously until it is reset. This cause a transistor 17 to turn on and actuate a ram downward movement relay R1. When the ram arrives at the lower limit of its movement, a lower LS 4 is opened causing a self-hold circuit 21 to produce an H level signal in accordance with an output of a one-shot multivibrator 18. The H level signal from the self-hold circuit 21 is delayed by a delay circuit 22 and turns on a transistor 23. As the result, a ram upward movement relay R2 is actuated. Because of the function of the one-shot multivibrator circuit 15, the ram will not restart when the start SW 3 is continuously depressed. The delay circuit 22 contributes to the longer operational life of a directional valve switching mechanism.